The present invention relates to an image recognition device which obtains an input pattern from a monochrome, two-valued image signal of a stationary or moving object to be recognised, compares the input pattern with a standard pattern, and recognises the object to be recognised, and in particular the present invention provides, in the pattern comparison, a new position shift detection method which detects at high speed the amount of shift of the input pattern compared with the standard pattern.
A conventional image recognition device, for example, a two-dimensional image recognition device, overlays as an image an input pattern and a standard pattern, and, by detecting the degree of alignment of the overlaid patterns, recognises the object to be recognised. Therefore, when making the pattern comparison, the two patterns must be accurately aligned, and conventionally, after moving the object to be recognised to a particular stationary position using for example an XY stage, an input pattern is obtained from television camera, and comparison processing of this input pattern with a standard pattern carried out. With this method, however, a mechanism is required to position the object to be recognised, so that, not only is the whole device resultingly more complicated, the pattern comparision time is increased by the positioning scan time, and many other problems tend to occur also.
The present inventors have, previously to the development of the present invention, developed a method whereby the positions of corresponding portions of the input pattern and standard pattern are detected on an image, and the positional deviations are computed, whereby the patterns are aligned as data. It should be particularly understood that it is not hereby intended to admit this concept as prior art to this patent application except to the extent in any case otherwise prescribed by applicable law. In this method, if there is noise present in the input pattern for example, the noise portion may be recognised falsely as part of the pattern, and in this case an incorrect pattern alignment will be carried out, and it has been established that there is a danger that proper recognition of the object will not be possible.